It's very hard not to give in to the pressure, I get that. But it's very hard for parents to force you to get baptized if you are firm in the face of that pressure. The trick is to be polite, yet adamant. Do not let them provoke you, but do not give in. Keep repeating that it is wrong to dedicate yourself when you do not yet feel you can be "whole souled in your devotion to Jehovah". Tell them that it would be hypocritical to dedicate yourself simply due to pressure from others. Tell them that it is such an important decision, that you take it very seriously and and that you must be sure and that you will pray to Jehovah for strength and wisdom to make that important decision, but that you will not do it until you feel convinced that he has responded to you with that wisdom and strength. Remind them that Jesus was thirty years old when he was baptized.
Repeat the above as needed.